SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb3716d3c460d86a261f38d8c74da1fe29fbf036dfec5a1fadf460ceeb992fcf' 
  AND token = 'XdC6JiVVFhpQajkEzMSB0qvzBI/kvWUITEEgoNJyAes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}